Diagnosis with Arterial Angiography
The following angiography techniques are used for diagnosing arterial disease:
- Ultrasound not true angiography is used to screen high-risk patients and to begin the investigation into possible arterial disease. Once arterial disease is suspected, more invasive methods (angiography) are indicated.
- MRI angiography with contrast (MRA): This uses the polarity of atoms in tissue to render an image. It has the highest accuracy in diagnosing arterial disease. Because of the contrast used, it has the highest likelihood of complications, but not the most severe. Its chamber is constricted and the machinery loud, so severe claustrophobia can make it unfeasible without sedation.
- CT angiography is a computed series of thin X-ray slices that are reconstructed into a continuous image. It is a good choice for those for whom contrast is contraindicated (allergies, kidney disease), but it is considered less accurate because of the absence of–or its reduced doses of–contrast for image enhancement. It is used for assessment of abdominal aortic aneurysms.
- Conventional (X-ray and fluoroscopic) angiography. Although it does not have the highest frequency of complications, it has the most severe complications and considerations, such as loss of control of arterial puncture, higher ionizing radiation, potential for nephrotoxicity and permanent kidney damage, and anaphylactic reaction to the contrast agent.
Arterial Angiography for Specific Arterial Conditions
- Abdominal aortic aneurysm: CT is the most useful.
- Thoracic aortic aneurysm: usually diagnosed incidentally by X-rays. Ultrasound, MRI, and CT imaging ordered for other reasons may discover a previously unknown thoracic aortic aneurysm. Once discovered, CT or MR angiography are the best ways to further analyze the pathology and follow its progress.
- Peripheral aneurysm: abdominal and pelvic CT angiography is used for symptomatic patients. MRA is useful as well, but not typically used due to expense and issues with metal implants.
- Aortic dissection: CT angiography is the most common method of imaging aortic dissection.
- Atherosclerosis: atherosclerotic plaques that can compromise blood flow or pose a risk for emboli are initially studied using ultrasound and then further investigated using CT angiography.
- Blunt aortic injury: CT angiography is the most common method of imaging traumatic aortic injury, usually because of its ready availability to most ER facilities where trauma patients first land.
- Carotid artery stenosis: cerebral angiography, using reduced contrast doses and small catheters, is used. It can allow visualization of the entire carotid arterial system for atherosclerosis, plaques, and collateral circulation which can affect management. Alternately, duplex ultrasound can be used, but its accuracy depends on the skills of the ultrasonographer.